We recommend that you always download the latest versions of the SL tools with the latest available SPS, as they contain the most recent corrections and are updated regularly. Please note that you can only download the SL tools, but not the SL Toolset.
SPS 21 is available since Sep 09, 2017.
The news are listed in the following SAP Community blog:
SUM is now offered in two versions. See section below for respective SUM scenarios, and this blog for details: http://blogs.sap.com/?p=520932.
Framework/Runtime Engine for automating configuration and verification of SAP systems.
Maintenance Planner allows planning changes in the landscape, based on SAP Solution Manager’s processes and data. Maintenance Planner can be leveraged by SAP Solution Manager 7.1 customers, and is mandatory for customers using SAP Solution Manager 7.2.
Maintenance Planner also enables a simplified up-to-date installation of a new system with a certain SP level, where the downloaded stack XML file can be handed over to Software Provisioning Manager.